The Contractor shall exert its best efforts to find additional tumor-associated substances which may have value for detecting, diagnosing, and/or screening for cancer in humans. Specifically, he shall: Use rabbits made "tolerant" to normal plasma and to extracts of normal tissue; He shall then inject cells and extracts of various tissues and tumors as specified, absorb the antisera and test it by counter immunoelectrophoresis, tytotoxicity, and immunofluorescence for specificity against fetal and tumor antigens; Test the antisera demonstrating specificity against a large panel of sera from normal controls and patients with different forms of tumors by sensitive direct forms of immunoprecipitations, immunofluorescence, and double antibody radioimmunoassays to see if the antisera are specific for the presence of carcinofetal antigens in human sera and if the results might prove useful as a diagnostic assay; and Use the antisera to facilitate the isolation of these tumor-associated antigens.